VISUAL SYSTEM DEVELOPMENT AND SYNAPTOGENESIS

视觉系统中突触发生的量化方面将是 从光感受器突触的数量和分布来看 蝇的第一个视神经丛。研究将集中在 阐明两个主要问题：1)什么是发展 突触数量和间距的决定因素；2)视觉有什么影响 对这些决定因素的经验？突触数量的测定将 在神经支配比率的自然差异中进行检查 突触前和突触后神经元之间的关系及定量EM分析 抽样技术。突触间距将分析在不同的 从冷冻断裂的突触前膜或 对突触后树突进行连续EM扫描，以测试一个突触的影响 站点附近的突触发生，因此，检查 突触发生与树突形态发生的关系。vbl.使用 类似的分析，视觉经验对突触群体的影响 在光照和/或照射后，将检查尺寸和分布 暗色，无论是在发育过程中还是在成年时期。 突触发生的定性方面将检查可能的改变 在激光诱导的神经元缺失后形成的突触类 果蝇发育过程中的突触后神经元及其各种突变体 要么缺乏光感受器功能，要么怀疑缺乏 反馈突触的类别或怀疑存在额外的 突触后神经元。所有这些都将进行定量分析-和 序列-EM技术，目的是了解 神经元通常在多接触突触(二联体、三联体等)处结合。 从扰动后形成的新奇组合。 预计这些研究将使我们了解到对 视神经元内突触群的大小、组成和分布 在这两种情况下发育过程中细胞数量变化的影响 视觉体验的差异。

Quantitative aspects of synaptogenesis in the visual system will be investigated from the number and distribution of photoreceptor synapses in the first optic neuropile of Musca. Studies will concentrate upon elucidating two major questions: 1) What are the developmental determinants of synapse number and spacing; 2) What influence has visual experience upon these determinants? Determination of synapse number will be examined amongst naturally occurring differences in innervation ratios between pre- and postsynaptic neurons and analyzed using quantitative EM sampling techniques. Synapse spacing will be analyzed at different developmental ages either from freeze-fractured presynaptic membrane or serial-EM of postsynaptic dendrites, to test the influence of one synaptic site upon synaptogenesis nearby and, consequently, to examine the relationship between synaptogenesis and dendritic morphogenesis. Using similar analyses, the effects of visual experience on synaptic population size and distribution will be examined following exposure to light and/or dark, either during development or in the adult. Qualitative aspects of synaptogenesis will examine possible altered synaptic classes formed either following laser-induced deletions of the postsynaptic neurons during development or in various mutants of Drosophila either lacking photoreceptor function or with the suspected absence of a class of feedback synapses or the suspected presence of an additional postsynaptic neuron. These will all be analyzed with quantitative- and serial-EM techniques with the aim of understanding the rules with which neurons normally combine at multiple-contact synapses (dyads, triads, etc.) from the novel combinations formed following perturbations. It is anticipated these studies will inform us about the regulation of synaptic population size, composition and distribution in visual neurons during development under eithr the influence of changes in cell number of differences in visual experience.